Plastic lenses are light weight, less broken, and dyeable, as compared with inorganic lenses. Therefore, in recent years, the application of the plastic lenses to optical materials for a spectacle lens, a camera lens, or the like has increased rapidly. Particularly, from the viewpoint of reducing the thickness of a lens, a plastic material having a high refractive index is desired, and, from the viewpoint of reducing chromatic aberration, a plastic material having a high Abbe number is desired. Among them, a plastic lens, which is comprised of a polythiourethane resin obtained by reacting a polythiol and a polyiso(thio)cyanate compound, has a high refractive index, and is excellent in impact resistance, dye-affinity, workability, and the like.
Further, in recent years, from the viewpoint of fashionability, lens having a two point frame, in which a frame for holding a spectacle lens is not provided at the periphery of a spectacle lens, has been used. When using the two point frame, in order to perform a drilling processing (two point processing) at both ends of the spectacle lens, the spectacle lens was required to have excellent workability and high strength.
Patent Document 1 discloses a polymerizable composition for an optical material containing a phenylene diisocyanate and a predetermined polythiol compound, and an ultrahigh refractive polythiourethane plastic lens having a refractive index of 1.7 or more, the lens being obtained from the composition.
Further, Patent Document 2 discloses a polymerizable composition for an optical material containing episulfide (thioepoxide). Additionally, it is described that an episulfide-based plastic lens having a refractive index of about 1.7 was obtained using the composition.
Further, Patent Document 3 discloses a composition for plastic lenses containing a compound having at least one radical polymerizable unsaturated double bond in a molecule, a predetermined alicyclic or aromatic polyisocyanate compound, and a predetermined polythiol compound, and discloses a plastic lens obtained from the composition.